from typing import Generator, Optional
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import jwt
from pydantic import ValidationError
from sqlalchemy.orm import Session

from app import crud, models, schemas
from app.core import security
from app.core.config import settings
from app.db.session import SessionLocal

reusable_oauth2 = OAuth2PasswordBearer(tokenUrl=f"/api/v1/auth/login")

def get_db() -> Generator:
    try:
        db = SessionLocal()
        yield db
    finally:
        db.close()

def get_current_user(
    db: Session = Depends(get_db),
    token: str = Depends(reusable_oauth2)
) -> models.User:
    try:
        payload = jwt.decode(
            token, settings.SECRET_KEY, algorithms=[security.ALGORITHM]
        )
        username: str = payload.get("sub")
        if username is None:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="Could not validate credentials",
            )
    except (jwt.JWTError, ValidationError):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Could not validate credentials",
        )
    user = db.query(models.User).filter(models.User.username == username).first()
    if not user:
        raise HTTPException(status_code=404, detail="User not found")
    return user

def get_current_active_user(
    current_user: models.User = Depends(get_current_user),
) -> models.User:
    if not current_user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user

def get_current_active_superuser(
    current_user: models.User = Depends(get_current_user),
) -> models.User:
    if not current_user.is_superuser:
        raise HTTPException(
            status_code=400, detail="The user doesn't have enough privileges"
        )
    return current_user 